Hemodynamic impact of pulmonary vasodilators on single ventricle physiology

The Fontan procedure is the palliative procedure for single ventricle physiology. Pulmonary resistance plays a key role in the success of this operation. There are conflicting data concerning the impact of pulmonary vasodilators on survival and functional capacity among Fontan patients.

The aim of this retrospective, single-center, nonrandomized study was to investigate the potential effect of pulmonary vasodilators on pulmonary vasculature in Fontan patients.

Twenty-seven patients with single ventricle physiology were enrolled. Eighteen patients were treated with pulmonary vasodilators: 9 patients after Glenn procedure or just after the Fontan completion (Group A) and 9 patients >5 years after Fontan completion (Group B). Nine patients after Glenn procedure were enrolled as a control group (Group C). The primary endpoint was to assess changes in hemodynamic profile and pulmonary branches' diameter after 2 right heart catheterizations. Adverse events were recorded.

Mean age ± SD was 3.2 ± 1.5 years (Group A), 26.8 ± 12.7 years (Group B), and 3.1 ± 1.0 years (Group C). Patients included in Group A had reduced arterial compliance (34.3 ± 15.4 vs 52.2 ± 24.2 mm² /[m² *mm Hg]; P = .03) at baseline compared with Group C. After treatment, Nakata index and pulmonary compliance increased in patients treated with pulmonary vasodilators (Group A), while remaining stable in the control group (Nakata index: +26 ± 24% vs -8 ± 17%, P = .003; pulmonary compliance +80 ± 49% vs -5 ± 30%, P = .001). Similar results were found in Group B (Nakata index: pre-168.6 ± 70.7 mm² /m² ; post-204.9 ± 97.5 mm² /m² ; P = .026).

Pulmonary vasodilators reduce pulmonary artery resistance and increase vascular compliance, pulmonary artery diameter, and cardiac output in Fontan patients. Therefore, pulmonary vasodilators may be used before the Fontan procedure in patients at high risk of Fontan procedure failure.